This invention relates to fluid handling systems for submarine hover control and more particularly to a multi-port rotary valve having substantially constant total flow resistance independently of the angular rotation of the rotary valve element.
The terms "hovering" or "hover" as used herein and as understood in the art to which this invention pertains refers to a submarine vessel operating condition wherein the vessel is ballasted in such a way that its depth below the water surface remains substantially constant and the horizontal velocity of the vessel is substantially zero with respect to the surrounding water. The term "total flow resistance" as used herein to describe the function of the rotary hover valve of this invention refers to the sum of the flow resistances of all flow paths through the valve and system for all angular valve element operative positions regardless of flow distribution.
In the past, submarine hovering systems have used three-way angle ball valves to control ballast water flooding of or discharging from two hovering tanks through the three ball valve ports. One port is an inlet and two are outlet ports, one for each of the two hovering tanks. Such valves are typically not hydrodynamically balanced nor are flow velocities through them controlled in a way to minimize flow generated noise. To maintain a constant volume of flow in prior systems using three-way rotary valves, the degree of valve opening was controlled to accommodate the variation in flow resistance required. Water was flooded to one vented tank and blown to sea from the other. The flood and blow tanks were switched as one tank filled and the other emptied. Since most prior systems do not use pumps, the two tank system requires continued use of the ship's air banks.